三江源农牧交错区土壤微生物碳、氮以及群落碳代谢特征对一年生禾豆混播的响应

通过对三江源农牧交错区常见一年生牧草（小黑麦、燕麦和箭筈豌豆）进行不同种植处理，于当年收获后测定耕层0~20 cm土壤养分及微生物学性质，来研究牧草种植对土壤质量的影响。结果表明：小黑麦单播下的MBC及MBC/SOC%高于其他处理，且显著高于箭筈豌豆单播及箭筈豌豆与燕麦双优（1∶2∶2）处理（P<0.05）；研究区土壤微生物主要利用碳源类型为羧酸类、酚类化合物、碳水化合物和氨基酸；聚类分析发现小黑麦单播和种植燕麦单优势种（1∶3∶1）、箭筈豌豆单优势种（1∶1∶3）及小黑麦+燕麦双优势种（2∶2∶1），对土壤微生物特性的影响相似。小黑麦单播会加快土壤有机质周转，燕麦和箭筈豌豆双优势种混播有增加土壤有机质的潜力；作为土壤质量的指示因子，MBC比MBN更敏感；不同处理下，土壤微生物对碳的利用强度和类型相似。综合考虑土壤微生物活性和生产特性，在实际生产活动中不适宜箭筈豌豆单播。

Response of Soil Microbial Biomass C and N,C Metabolism Characteristics of Microbes to Grass-Legume Mixtures of Annual Artificial Grassland in Sanjiangyuan Region

Different mixed sowing treatments of 3 annual forages (i.e. Triticale,Oats and Vicia sativa) in agro-pastoral ecotone of Sanjiangyuan region were carried out,and soil microbial properties,such as microbial biomass carbon and nitrogen,and carbon metabolism activity of microbes within 0~20 cm plough layer,were determined after harvest. The results showed that MBC and MBC/SOC% under triticale monoculture were higher than those under other treatments,and significantly higher than those under the Vicia sativa unicast and the 1:2:2 treatments (P<0.05),while no significant difference in other indicators between treatments was found. The carbon resources used by the soil microbes in the study area mainly included the carboxylic acid,phenolic acids,carbohydrates and amino acids. The cluster analysis found that the treatments of triticale unicast,1:3:1,1:1:3 and 2:2:1 had similar effects on soil microbial characteristics,and the microbial activity of which was greater than that under other treatments. The above results indicated that triticale unicast may promote turnover of soil organic matter,while mixed sowing of oats and Vicia Sativa had a potential to increase soil organic matter. As the indicator of soil quality,MBC was more sensitive than MBN. Soil microbes had similar carbon utilization intensity and types under different treatments in the study area. Considering the soil microbial activity and production characteristics,Vicia sativa unicast in the actual production activities was not recommended.